With two days until South Carolina’s Republican presidential primary, former Massachusetts Gov. Mitt Romney holds a 10-point lead over former House Speaker Newt Gingrich, according to a new NBC News/Marist poll of the GOP contest in that state.

But a day after Monday night’s Republican debate – where Gingrich’s performance was considered strong and Romney’s uneven – the poll also shows the former speaker gaining considerable ground on the GOP frontrunner.

Overall in the two-day survey – conducted Monday and Tuesday – Romney gets the support of 34 percent of likely Republican primary voters in South Carolina, including those who are undecided but leaning toward a candidate.

Yet the numbers are strikingly different before and after the debate on Monday, when Romney stumbled over whether he would release his tax records (he later said he would do so in April). Also in that outing, Gingrich drew cheers – and even a standing ovation from some – in response to a question about whether his rhetoric about food stamps and janitorial work for poor children was racially insensitive.

“The fact is that more people have been put on food stamps by Barack Obama than any president in American history,” Gingrich answered. “I know among the politically correct, you're not supposed to use facts that are uncomfortable.”

He later added, “I believe every American of every background has been endowed by their creator with the right to pursue happiness. And if that makes liberals unhappy, I'm going to continue to find ways to help poor people learn how to get a job, learn how to get a better job and learn some day to own the job.”

Another GOP debate takes place on Thursday evening.

What a difference one debate makesOn Monday before the debate, Romney led Gingrich in the poll by 15 points, 37 percent to 22 percent. But on Tuesday, that advantage narrowed to just five points, 31 percent to 26 percent.

“The numbers on Tuesday were very different than the numbers on Monday,” says Lee Miringoff, director of the Marist College Institute for Public Opinion, which conducted the survey.

And a similar change occurred among likely South Carolina primary voters who are evangelical Christians. On Monday, Romney led Gingrich here, 36 percent to 22 percent, with Santorum at 18 percent. On Tuesday, it was Gingrich at 27 percent, Romney at 22 percent, and Santorum at 19 percent.

While Gingrich gained ground on Romney the day after the GOP debate, his poll position in South Carolina has declined markedly since December, when he led the former Massachusetts governor in the NBC News/Marist poll, 42 percent to 23 percent.

The Bain dog doesn’t bite – at least for nowRomney also can take comfort with this finding from the poll: His past work at Bain Capital doesn’t seem to bother South Carolina Republicans.

Sixty-one percent of GOP primary voters – as well as 42 percent of all registered voters in the Palmetto State – agree with the statement that investment firms like Bain help the U.S. economy. And they agree that while some companies fail or are restructured, others succeed and that’s how the free market works.

By comparison, just a quarter of likely GOP primary voters – plus a third of all registered voters – agree with the statement that investment firms like Bain hurt the U.S. economy when they take over a company; when they lay off workers and reduce their pay; and when they make money for the firm whether or not the company succeeds.

And a plurality of likely GOP primary voters – 23 percent – find Romney to be the Republican presidential candidate who best understands their problems. That’s compared with 22 percent for Gingrich, 18 percent for Paul and 16 percent for Santorum.

• 39 percent of likely Republican voters in the state believe that the ability to beat President Barack Obama in November is the most important candidate quality, and that’s nearly double the percentage who said that in December’s NBC News/Marist poll of South Carolina;

• a majority (56 percent) think Romney has the best chance of beating Obama;

• a plurality (30 percent) say that Romney has been the candidate who has spent the most time talking about the issues, while another plurality (41 percent) say Gingrich has been the one who has spent the most time attacking his opponents;

• another plurality (36 percent) say they like Paul the least;

• and Obama’s job-approval rating in South Carolina – among registered voters – is 44 percent.